1. Field of the Invention
The present invention is generally directed to a depth sounder, such as employed in a fish finding apparatus. More particularly, the present invention is directed to a depth sounder and method for identifying both desired sonar targets and undesired echos.
2. Description of Related Art
The use of sonar echo sounding for recreational and commercial fish finding purposes is widespread. However, many find the presentation of "raw" echo sounder data to be difficult to interpret, and therefore favor devices which will translate received echos into pictures of fish or other icons which are easily recognized by the user. Conventional sounder devices having object identification features of this nature are extremely limited in their abilities, and are often "fooled" by noise of various types. Additionally, echo sounders are inherently subject to interference from other sounders operating in their vicinity. This interference causes vertical streaks to appear on the display of the sounder, causing clutter and difficulty in interpretation. Current fish finding technology utilizes closed feedback gain control loops to eliminate noise based upon the amount of energy being detected in a water column. This approach is effective in reducing interference from most noise sources and increases the confidence for fish detection. However, closed feedback gain control loops generate a fluctuation in the visual representation of an echo received from the bottom of the subject body of water, causing distortions destructive to interpretation of data indicative of other structure in the body of water.
Accordingly, the need exists for an effective and simple echo sounding solution for identifying objects in a body of water. The present invention fills these and other needs, while overcoming the drawbacks of prior devices.